<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    .outer {
      position: relative;
      width: 400px;
      height: 400px;
      background-color: gray;
    }

    .outer .box {
      width: 100px;
      height: 100px;
      background-color: aqua;
      margin: 10px;
      float: left;
    }

    /* .box1 {
      float: right;
    } */
  </style>
</head>

<body>
  <div class="outer">
    <div class="box box1">1</div>
    <div class="box box2">2</div>
    <div class="box box3">3</div>
  </div>
</body>

</html>